poj 3784 Running Median/sbt

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原题链接：http://poj.org/problem?id=3784

动态地求中位数，套平衡树做就行了。。。

代码如下：

#include<iostream>#include<algorithm>const int Max_N = 10000;struct SBT *null;struct SBT{int val, size;struct SBT *ch[2];inline void push_up(){size = ch[0]->size + ch[1]->size + 1;}}stack[Max_N << 2], *root;int sz = 0;void init(){null = &stack[sz++];null->val = -1, null->size = 0;root = null;}void rotate(SBT* &x, int d){SBT *k = x->ch[!d];x->ch[!d] = k->ch[d];k->ch[d] = x;k->size = x->size;x->push_up();x = k;}void Maintain(SBT* &x, int d){if (x->ch[d] == null) return;if (x->ch[d]->ch[d]->size > x->ch[!d]->size){rotate(x, !d);} else if (x->ch[d]->ch[!d]->size > x->ch[!d]->size){rotate(x->ch[d], d), rotate(x, !d);} else{return;}Maintain(x, 0), Maintain(x, 1);}void insert(SBT* &x, int val){if (x == null){x = &stack[sz++];x->val = val, x->size = 1;x->ch[0] = x->ch[1] = null;} else {int d = val > x->val;insert(x->ch[d], val);x->push_up();Maintain(x, d);}}int find_kth(SBT *x, int k){int t = 0;for (; x != null;){t = x->ch[0]->size;if (k == t + 1) break;else if (k <= t) x = x->ch[0];else k -= t + 1, x = x->ch[1];}return x->val;}int main(){#ifdef LOCALfreopen("in.txt", "r", stdin);freopen("out.txt", "w+", stdout);#endifinit();int i, t, n, q, val, cnt;scanf("%d", &t);while (t--){sz = cnt = 0;init();scanf("%d %d", &q, &n);printf("%d %d\n", q, (n + 1) >> 1);for (i = 1; i <= n; i++){scanf("%d", &val);insert(root, val);if (i % 2 != 0){printf("%d ", find_kth(root, ((root->size) >> 1) + 1));cnt++;}if (cnt && cnt % 10 == 0) cnt = 0, printf("\n");}printf("\n");}return 0;}

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